In recent years, halogen lamps have been widely used suddenly, and they are being spread over various fields. In particular, as for domestic use, commercial power sources of 100 V, 120 V, 220 V and 240 V have been once lowered to a lower voltage of, for example, 12 V, by a transformer so that the halogen lamps have been used. In this case, there arose problems such that &lt;1&gt; the cost of the transformer is high, &lt;2&gt; according to the relationship of (dissipation power=voltage X electric current), when the commercial power-supply voltage is lowered to 12 V, in the same dissipation power, a current value becomes larger than the case where the commercial power-supply voltage is applied directly to a halogen lamp, and a trouble of contact with a socket, etc. easily occurs.
Therefore, it has been desired recently that a halogen lamp for general illumination at home including illumination at shops is shifted from the method of using the voltage which is lowered to 12 V to the method of directly using the commercial power-supply voltage. In this case, even if a special socket and light apparatus are not used, a halogen lamp can be used without using a transformer, etc. by thrusting or inserting it directly into a light apparatus to which a socket is attached.
However, in the case where lamps whose dissipation power is the same are compared with each other, a commercial power-supply voltage-type (100 to 240 V) halogen lamp has serious manufacturing and use problems in handing a filament because a diameter of the filament must be smaller and its length must be longer than a low-voltage-type halogen lamp whose lighting voltage is, for example, 12 V and 24 V.
These problems are such that: &lt;1&gt; since a filament is very thin, it is deformed during lighting and it easily causes sag, and since a filament is easily disconnected because of a vibration from the outside, a support is necessary; &lt;2&gt; since a diameter of the filament is small, it is very difficult to wind a support around the filament, and in the outrageous case, the filament is disconnected at the winding portion during the winding; and &lt;3&gt; the filament is frequently deformed and disconnected because of its thinness, so it is difficult to attach it to an envelope, and not only production using the hands but also mass production by automation are unthinkable.